I think his technical involvement with Apple started and ended in the 70's, when he helped assemble the Apple I boards that Woz designed. I don't know if he's ever coded. I found a video once of him demonstrating NextSTEP, but it stops right before he's about to demonstrate the programming environment, so I don't know if he even demoed that part or got someone who could code to do it.

What he has done personally is some of the design; he's listed on the design patents for the glass staircase at one of the main Apple stores, and personally designed one of the glass cubes.